this lecture describes the basic anatomy of the lungs and thoracic area and goes over the basics for the mechanics of breathing. the first part deals with lung anatomy. the right and left lungs are divided into upper and lower lobes by oblique fissures, and the right has a middle lobe that is delineated by the horizontal fissure. in the left lung, the lingula is a protuberance that is homologous to the right middle lobe and is formed by the cardiac notch. the lungs are further divided into 10 "bronchopulmonary" segments, which are functional units that are separated by connective tissue septa. air comes into the lungs first through the trachea, which then branches into primary, secondary, and tertiary bronchi, which branch off into the right and left lungs (primary), individual lobes (secondary), and individual bronchopulmonary segments (tertiary). the root of the lung is called the hilum and contains the pulmonary arteries, veins, nerves, and lymph nodes. within the bronchopulmonary segment, pulmonary arteries snake down the center, supplying oxygenated blood, while the pulmonary veins collect deoxygenated blood and follow the intersegmental CT septa.
next we look at the mechanics of breathing. the pleura is introduced as the bursa that surrounds the lungs and reduces friction. much like the pericardium, it has a parietal and visceral layer and is filled with a lubricating fluid. the visceral layer in this case adheres to the lungs and the parietal layer adheres to the diaphram, pericardium, and thoracic cage. the space between the visceral and parietal pleura is called the pleural cavity and is the space in which the lungs can expand into during inspiration. a couple of pathologies related to the pleura are mentioned: pleurisy is inflammation of the pleura, causing the visceral and parietal layers of the pleura to fuse together and not allow the lung any room to expand. pneumothorax is the filling of the pleura with liquid, which causes the lungs to collapse.
the structure of the ribs is looked at: ribs 1-7 are "true ribs" and insert directly into the sternum, ribs 8-10 are "false ribs" and insert onto the costal margin, and ribs 10-12 are "floating ribs" which do not insert on bone or cartilage. the ribs origin has two types of joints: costovertebral joints, which are the joints between the heads of the ribs and the articular facets of two adjacent vertebras, and costotransverse joints, which are the joints between the transverse processes of the vertebrae and the tubercle of the ribs. these joints allow the ribs to be pulled up and out, allowing the thoracic cage to increase its transverse (from side to side) as well as anterior-posterior diameters, the first step in inspiration. the external intercostal and parasternal intercostal muscles lift the ribs as the diaphram pulls the pleura downward, producing negative (below atmospheric) pressure in the pleura, which expands the lung and begins inspiration. expiration can occur passively, in which the lungs elastically recoil and the inspiration muscles relax, or actively, in which the abdominal muscles pull the ribs back out and the diaphragm pushes back upwards.
questions
1. what is the advantage of the separation of the lungs into lobes via fissures?
2. what are the upper and lower lungs separated by?
3. what is the right middle lobe formed by?
4. what is the lingula formed by and what is it homologous to?
5. what is the apex of the lung called and where does it extend to?
6. what is the root of the lung called and what does it contain?
7. describe the role of the trachea in maintaining an open airway.
8. describe the subdivision of the bronchi in relation to their location/function in the lung.
9. what is one important role of elastic tissue and smooth muscle in the lungs?
10. describe the symmetry of the primary bronchi.
11. what are bronchopulmonary segments and how many are there?
12. describe the locations of the pulmonary arteries, veins, and lymphatics in a bronchopulmonary segment.
13. describe the organization of lymph drainage in the lungs.
14. what does lymph from the lung often contain?
15. describe the location and function of the bronchial arteries and veins.
16. what effects do parasympathetic nerves have on the lungs?
17. what effect do the sympathetic nerves have on the lungs?
18. what is the pleura?
19. what does the parietal pleura adhere to?
20. what is the pleural cavity?
21. what are the costodiaphragmatic and costomediastinal recesses?
22. what is pleurisy?
23. what is pneumothorax?
24. describe the costovertebral joints.
25. describe the costotransverse joints.
26. describe the costosternal joints.
27. what are "true ribs"?
28. what are "false ribs"?
29. what are "floating ribs"?
30. describe the actions required for inspiration.
31. what are the two diameters increased during the movement of the ribs during inspiration?
32. what are the accessory muscles involved in raising of the ribs?
33. what is the diaphram and what goes through it?
34. what is the phrenic nerve and what does it innervate?
35. what is passive vs. active expiration?
origins and insertions for...
36. external oblique
37. internal oblique
38. transversus abdominis
39. rectus abdominis
40. how do the abdominal muscles aid in respiration?
41. how do the abdominal muscles move the vertebral column?
42. what do the intercostal nerves innervate and where do they originate on the spinal column?
answers
1. separation promotes more uniform expansion of the lungs, allows the upper lobes to "expand unimpeded".
2. the oblique fissure
3. the horizontal fissure
4. the cardiac notch, homologous to the right middle lobe.
5. called the cupola, and extends into neck above the 1st rib
6. called the hilum, location of passage of bronchi, pulmonary artery and vein, nerves, and lymph nodes.
7. the trachea contains cartilage rings that maintain patency, and the trachealis muscle maintains wall tension.
8. primary bronchi branch off into each lung, secondary bronchi branch off into each lobe, tertiary bronchi branch off into each bronchopulmonary segment.
9. facilitating passive expiration
10. the right primary bronchi extends down straighter than the left, allowing particulates to flow into right lung more easily.
11. there are 10 bronchopulmonary segments and they are functional units of the lung separated by CT septa and filled with tertiary bronchi.
12. the pulmonary artery flows down the middle of the segment, the pulmonary vein flows near the intersegmental CT septa, and the lymphatics follow the veins.
13. superficial and deep plexuses drain into the bronchopulmonary nodes in the hilum of the lungs.
14. lymph from the lung often contains lung macrophages which have injested carbon particles.
15. the bronchial arteries branch off of the aorta and supply the lung tissue with oxygenated blood. the bronchial veins drain deoxygenated blood from the lung tissue and follow the intercostal veins to the azygos veins.
16. the vagus nerve causes bronchoconstriction and activates mucus glands
17. bronchodilation
18. the bursa that surrounds the lungs that has a parietal and visceral layer.
19. thoracic cage, diaphragm, pericardium
20. the space in between the visceral and parietal layers that is filled with a viscous lubricating fluid.
21. the spaces in between the visceral and parietal layers of pleura into which the lung expands.
22. inflammation of the pleura that may lead to adhesions between pleural layers, limiting lung movements.
23. entry of fluid between the visceral and parietal layers of pleura causes collapse in lung.
24. joints between the head of the ribs and the facets of two adjacent vertebral bodies, with ligaments radiating outward from rib
25. joints between tubercle of the rib and transverse processes of vertebrae, with costotransverse ligaments.
26. ribs that articulate with the sternum via costal cartilage.
27. ribs 1-7, articulate directly onto sternum
28. ribs 8-10, articulate onto costal cartilage of ribs above
29. ribs 11,12, do not attach to sternum or costal cartilage.
30. the external and parasternal internal intercostal muscles raise the ribs, and the diaphragm lowers
31. the anterior poster and the transverse diameters
32. serratus posterior, levator costarum, SCM, scalenes
33. a ring of muscle around a central tendon attached along the costal margin. penetrated by IVC, aorta, esophagus
34. nerve that originates in C3,4,5, innervates fibrous pericardium, diaphragm, pancreas, gall bladder.
35. passive expiration comes from the relaxation of the inspiration muscles and the elastic recoil of the lungs. active expiration comes from abdominal muscles pulling down on the ribs, as well as pushing the diaphram upwards to collapse the lungs.
36. O: lower 8 ribs, I: iliac crest, pubis, linea alba
37. O: iliac crest, I: costal margin, linea alba, symphysis pubis
38. O: costal margin, iliac crest, I: linea alba
39. O: symphysis pubis, I: costal margin, cartilage of ribs 5,6,7
40. the rectus abdominus and obliques depress ribs during expiration
41. the rectus abdominus flexes and the obliques abduct and rotate.
42. they innervate the intercostal muscles (T1-T12) and the abdominal muscles (T6-L1)
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